Sweetness can be a minefield in the pathway of current consumer migration toward low-calorie and natural foods and beverages. Science has long demonstrated that humans are hardwired to love sweets. Throughout early history, sweet taste was paramount to survival, helping humans distinguish edible, nutritious and caloric foods from poisonous, inedible or low-caloric ones. This is a fact lately stressed by Brian Wansink, PhD, one of the premier researchers into the crossroad where eating behavior and nutrition meet.
The discovery of natural sweeteners, such as honey, led to their use to impart sweetness to other foods. While honey was probably one of the earliest sweets—consumed since prehistoric times—sugar cane is believed to be first cultivated. Evidence of processed sugar cane has been found in Papua, New Guinea, dating back 8,000 years, and mounds of processed hard sugar were documented about 2,500 years ago during the Persian invasion of India.
Sugar cane trade flourished in late 16th century, when sugar cane plantations were established in the New World. The production of refined sugar started in England in the 18th century, with beets being identified as an alternate source of sugar around the same time. Overall, these sweeteners were costly enough to be used only in the rare treat.
When the cost of sweeteners plummeted in the Industrial Age, Western diets began to include a large amount of sweetened foods. Today, too many people have eating behaviors that typically suffice or exceed daily caloric needs, predominantly through sweet items.
It’s clear that humans continue to have the same strong preference for sweet flavors. This is proven by the increasing global human consumption of sugar, which went from about 5.1kg per capita at the beginning of the 20th century to about 23kg per capita, according to the “Groupe Sucres et Denrees (S&D) 2015” report.
Obesity and diabetes were found to increase in parallel, and consumption of added sugars was regarded as a significant contributor to the worldwide obesity epidemic—as demonstrated in research by Adam Drewnowski, PhD, recognized as a world leader in studying how obesity intersects with individual and cultural/socioeconomics of diet and health.
Scores of studies indicate that calories in overweight/obesity typically are derived from multiple sources, not just sweets. For the purposes of measurement of energy intake, a calorie is a calorie—no matter its source—yet sweets get a big share of the blame for the obesity epidemic. The “2014 Food & Health Survey,” conducted by the International Food Information Council (IFIC) found that only 29% of Americans correctly believe that all sources of calories equally contribute to weight gain. Meanwhile, the survey found 70% of Americans are actively cutting back their added sugar intake.
This perception, one that originally led to the runaway success of low-calorie sweeteners that taste sweet while contributing fewer or no calories, has more recently been modulated by consumers’ interest towards natural products and clean labels.
All these factors have converged in the past decade. The combination of multiple consumer demands and increases in both nutritional and food product development science have led to extensive development efforts for natural, low-calorie sweeteners that are able to respond to both these primary consumer desires.
A Matter of Perception
Although sweetness is received positively by most consumers, not all sweeteners are perceived the same way. While individual sensitivity to sweetness varies, sometimes considerably, the sweetener identity and the perceived intensity of bitterness were found to have a larger impact on overall sweetness acceptance, according to the paper “Perception and Acceptance of Sweeteners,” by Jeannine Delwiche, PhD, and Amanda Warnock, published in the “American Chemical Society Symposium Series” Sweetness and Sweeteners (2008).
Studies exploring sweet taste perception and preference led to the identification of the sweet taste receptor found in the mouth, gut and pancreas. Interestingly, this sole heterodimer consisting of subunits T1R2 and T1R3 is able to respond to the chemically-diverse range of sweeteners, because each subunit provides multiple ligand sites able to bind the various sweetener molecules, as described by Jiang, et al, also in the Sweetness and Sweeteners series.
Recent studies, including by Drewnowski and his team, have provided an even better understanding of the mechanisms through which sweeteners actually reduce pain and activate the pleasure centers in the brain. These perception differences, alongside consumer views regarding the impact of sweeteners on health, are revealing insights into comprehensive aspects of what modulates consumer product choices.
This was confirmed by the research group Mintel Inc. Its “2014 Food & Health Survey” data indicate that “low/no/reduced sugar” and “low/no/reduced calorie” were the fastest growing claims related to sweeteners. The group also found that 51% of respondents try to limit or avoid added sugars in their product choices, and HFCS (high-fructose corn syrup), fructose and aspartame are among the sweeteners preferentially avoided.
In contrast, Mintel’s “2014 Customer Survey” found that honey is regarded as “good for health” by 60% of the respondents, compared to granulated sugar among a mere 10% of those polled. (However, the group also found that more than 55% of the US households continue to use white granulated sugar.)
The statistics confirm that—despite expressed concerns—the taste, performance and low cost of white granulated sugar continue to position it as the “go-to” sweetener. In fact, 54% of the respondents listed taste as the main factor in their sugar/sweetener purchase decision, while only 18% of the respondents believe that sugar substitutes taste as good as sugar.
Of the more caloric options, sucrose—white granulated sugar—has been the primary sweetener for centuries, and with good reason: Its clean taste, good stability and relatively low cost quickly established sugar as the gold standard for sweetness flavor and profile. Additionally, sucrose has important functionality in various foods, impacting texture, flavor, color (e.g., browning via the Maillard reaction)—or acting as a bulking agent, preservative or fermentation substrate.
Making Sweeter Better
Ensuring the right sweetness note and intensity level is paramount for success of any sweet food product introduced to the marketplace. To ensure the right sweetness, 21st C. product developers have at their disposal a wide toolbox of cutting-edge sweeteners that contribute an unprecedented spectrum of sweetening performance in terms of intensity, flavor notes, temporal profiles, balance, finish and aftertaste.
Sweeteners are typically categorized based on two major criteria: caloric content and their status as natural or artificial. Some of these sweeteners also have other effects on the food systems being formulated, impacting their viscosity, mouthfeel, moistness, texture, etc.
Most traditional caloric sweeteners are perceived as “natural.” They include sugar, honey, molasses, agave and maple syrup, to name just a few. Despite their caloric contribution, the perception of these sweeteners as natural appeals to consumers. Besides sweetness, some of these caloric sweeteners have the capacity to bring additional functionality to the products being formulated.
High fructose corn syrup is a liquid caloric sweetener similar in chemical composition, flavor and functionality to sucrose, and was developed as a lower- cost alternative to sucrose (table sugar) for industrial applications. Despite the multiple studies consistently showing no differences between HFCS and sucrose in terms of their health impact, HFCS has experienced a flood of negative press. In recent years, and as a result, many consumers now perceive white granulated table sugar as more “natural.”
Some of the food system attributes impacted by the caloric sweeteners include flavor, viscosity, mouthfeel, moistness and texture. And, of course, many are used not only to sweeten, but also to impart their own unique flavor profiles. Honey, maple syrup and molasses are almost exclusively used when their flavor contribution is desirable in the end-product.
Most pure caloric sweeteners have about 4 kcals/g, because of their unique flavors beyond sweetness, some can be used more sparingly.
Agave, yacon syrup and polyols are caloric sweeteners often used for real or perceived health benefits—the so-called “health halo.” They might need fewer calories-worth of ingredient to achieve the same sweetness intensity as sugar or, in the case of polyols especially, a non-cariogenic response. Polyols also are lower in calories and range from about one twentieth to one quarter as sweet as sucrose. In formulating products for diabetes and blood-sugar management, certain sweeteners are included to lower the glycemic response of the food.
Consumer concern over the caloric contribution of some of these sweeteners has fed the steady influx of low- and zero-calorie alternatives for well over half a century. The low-caloric contribution depends on the intensity of the active sweetening compounds. Some have a relatively high sweetness intensity compared to sucrose.
Artificial sweeteners have been around for decades or longer. Saccharine was developed in the late 1800s, and aspartame and acesulfame K (Ace-K) came out in the 1960s. Even sucralose is in its second generation, having been around since the 1970s. Use of these sweeteners has been extensive, each having its own set of advantages and issues related to their taste, linger and temporal profile.
More recently, there has been a major shift toward natural sweeteners, spurred by the rediscovery and development of natural high-intensity sweeteners, such as extracts of stevia and lo han guo (monk fruit). These are noted for a very high concentration of sweetness about 150-300 times as sweet as sucrose depending on the specific sweetener formulation.
Formulating for Sweetness
Many aspects need to be considered when formulating with sweeteners, depending on the food or beverage application being developed and its processing requirements, storage conditions and desired shelflife. Since sweeteners are primarily used to provide sweetness, their sweetening power is the first aspect to consider. Then, the sweetness temporal profile—or the perception of sweetness intensity over time—must be considered, as well.
Some sweeteners, such as stevia, have a lag time from the moment they are placed in the mouth, with sweetness being perceived slightly later than for sugar. Ace-K, on the other hand, has a rapid perception. This makes it ideal to blend with those sweeteners that exhibit such lag time—resulting in a combination that is perceived to be more like sugar.
Some sweeteners, such as sucralose and aspartame, have a lingering sweet taste, often complicated with other notes. The formulator might need to consider flavors or modifiers to mask these properties, depending on the nature of the product being formulated.
When considering intensity, formulators should keep in mind that combinations of sweeteners could exhibit higher sweetness intensity than the sum of the individual components because of potential synergies. Sweeteners are frequently combined for flavor/profile balance, but any synergies among them could be beneficial because of potential cost-reduction opportunities.
The actual flavor of sweeteners is no less important. Many sweeteners have a relatively neutral flavor, but several popular sweeteners, such as maple sugar, agave or stevia extract, come with distinct flavor notes. These specific notes can be compatible or even beneficial for some food systems.
Formulators today have a much wider range of flavor modifiers and maskers available to help obtain the desired flavor note of a product. Most polyol sweeteners are known to impart a “cooling” effect. They are especially favored in mint-flavored products, such as gum and candy. Erythritol is a popular bulk sweetener for low-calorie and natural sweetening systems because of its low-caloric contribution. However, such significant cooling effects should be considered to ensure compatibility to the application being formulated.
Caloric contribution, of course, has been a driving force behind development in sweet formulations. The development of low-calorie applications using sweeteners is particularly challenging when the sweetener normally provides a primary functionality beyond sweetness. This becomes pronounced in baked applications, where sucrose provides considerable bulking.
Besides sweetness, flavor note, caloric contribution and health impact, formulators also should keep in mind that specific physical properties of bulk sweeteners impact the attributes of the applications being developed. Applications such as baked goods or jams take advantage of the bulk provided by granulated sugar or dextrose. The formulator wishing to develop a low- or sugar-free version needs to identify solutions addressing the loss of bulk.
Sugar and other bulk sweeteners are extensively used by food formulators for their impact on the texture and mouthfeel of many foods and beverages.
Formulation of low-sugar and sugar-free versions of current foods will require alternate solutions to restore the missing texture. The particle size of sweeteners needs to be considered in dry-blended systems to ensure their uniformity, visual appearance and dissolution properties, to name a few. The sweetener particle size can have an effect on the overall texture of a final product, as well.
In some applications, the loss of bulk is associated with a change in product density. In such cases, the formulator will need to maintain the concentration of other ingredients on a serving volume rather than weight basis, to maintain compatibility with the full-sugar versions. This is important in beverages, too.
The polyols are of interest in respect to bulking, because of their similar sweetness intensity yet lower caloric content compared to sucrose. This is only assuming a particular polyol’s specific properties are compatible with the flavor profile of the application being formulated. Erythritol, especially in combination with other sweeteners, such as stevia, has become a preferred sweetener system for such formulation needs.
Sweetness and Health
The health impact of sweeteners isn’t limited to caloric content. With diabetes and other blood-sugar management syndromes at epidemic levels, glycemic index—a measure of how fast blood sugar increases after ingesting a food—has become an important aspect of formulation for many processors.
Some caloric sweeteners, such as agave syrup and coconut palm sugar, have a relatively low glycemic index, indicating a slower release of glucose in the blood. On the other hand, agave syrup typically is anywhere from 60-90% fructose.
On another note, some sweeteners, such as polyols or fructo-oligosaccharides, can have a laxation threshold ranging between 15-100g per day. To assess potential gastric distress, when formulating applications using these sweeteners, the product developer needs to consider not only the amount of sweetener used in the final product, but also how much of the final product could be typically consumed.
While most simple sugars support the growth of bacteria responsible for dental cavities, such as Streptococcus mutans and several lactobacilli, most polyols and low-/zero-calorie sweeteners are non-cariogenic. This attribute is taken advantage of in applications where cariogenicity is a concern due to the large residence time in the mouth, such as chewing gum or candy.
The Sweet Solution
The solubility of sweeteners is an important factor to consider in formulating many foods and virtually all beverages. While most sweeteners are readily soluble in water, the lower solubility of some sweeteners become a limiting factor for the process and/or formula of selected applications. Powder blend products are an example—the consumer stirs them in beverages or other liquid food systems and expects that all the ingredients will mix and dissolve quickly and thoroughly.
A sweetener’s stability can impact the processability or shelflife of applications using them. For instance, many sweeteners are heat-sensitive, hence not appropriate in applications processed using higher temperatures. Also, the humectant capacity or water activity (aW) of sweeteners affect the stability of formulated food systems, as higher humectant capacities indicate that the sweetener would retain more moisture, preventing a hard, dry texture.
Knowing the humectant capacity of a sweetener will be important in formulas where they do not completely dissolve. Of even greater concern, such factors also facilitate more intense microbial activity. This process is in many cases detrimental, leading to the spoilage of foods.
Of course, not all microbial activity is undesired. Specific applications take advantage of the ability of some sweeteners to act as substrates ensuring efficient microbial growth. Think bread and beer. Sugar is an important component of the substrates used to grow carefully selected microbial cultures.
Hygroscopicity—the ability of a sweetener to attract and hold water from the local environment—is therefore of primary concern. Hygroscopic sweeteners are less stable if able to pick up moisture from the environment, so applications formulated with them will require packaging with good moisture barriers to ensure an acceptable shelflife.
The color of foods and beverages can be susceptible to the color-generating chemical reactions caused by, or related to, a particular sweetener. A typical example is caramelization, triggered by a heating of sugar which leads to breakdowns and re-arrangements (Maillard reactions) involving reducing sugars and amino acids.
In some instances, these transformations are advantageous, such as when developing the color of baked applications or in applications where the slight tan or light-brown coloring is triggered by some mono- or disaccharides. Such colors are perceived by consumers as “more natural” and more flavorful.
What Price Sweet?
The food product developer considering what sweeteners to use in formulating various applications must carefully consider cost and regulatory status. As inexpensive as sugar seems, it often is a more expensive option when usage levels are factored in. Many formulators have modified sugar-based products to use hybrid sweetener blends to decrease costs.
For example, a product sweetened solely with sugar can be reformulated with a combination of sugar and a low- or zero-calorie sweetening ingredient, with the first aim not to reduce calories, but to reduce the overall costs. While some of these high-intensity ingredients might seem expensive by weight, they can be highly cost-effective, considering how little is needed for the required sweetness intensity. However, the ability to cut down costs using this approach can be hindered by other requirements, such as when sweetener blends are required to use natural components.
The regulatory considerations when formulating with a sweetener system could soon include their “natural” status. The current, highly debated issue of “what is natural” (given that “natural” is not yet legally defined) is being reviewed heavily with decisions by ruling bodies expected in the near future.
It is possible that, in some cases, warning labels could be applicable for some ingredients. Also, the ingredient’s status in countries where the product will be marketed might need to be reviewed.
Stevia has generated some media controversy, as have other, more established sweeteners, such as HFCS, based on manufacturing methods and methods of extraction, in spite of the actual safety of said methods. Still, having full knowledge upfront of the regulatory status of the sweeteners being considered will save time and streamline the development process.
Sanford Peelle, CFS, and Catalin Moraru, PhD, are with International Food Network LLC (IFN). Both have extensive product development expertise encompassing the use of a variety of sweetener systems in formulating various foods and beverages. Since 1987, IFN has provided a full range of research and development services to leading food, beverage, supplement and ingredient manufacturers. IFN engages in a service-oriented, collaborative approach to provide innovative solutions, value-added expertise and fresh perspectives at each step of the product life-cycle, from concept to commercialization. For information, reach Peelle and Moraru at 607-257-5129 or go to www.intlfoodnetwork.com.